course will spare its territory from devastation, carry on
the war at the expense of the enemy, excite the ardor of its soldiers,
and depress the spirits of the adversary. Nevertheless, in a purely
military sense, it is certain that an army operating in its own
territory, upon a theater of which all the natural and artificial
features are well known, where all movements are aided by a knowledge of
the country, by the favor of the citizens, and the aid of the
constituted authorities, possesses great advantages.

These plain truths have their application in all descriptions of war;
but, if the principles of strategy are always the same, it is different
with the political part of war, which is modified by the tone of
communities, by localities, and by the characters of men at the head of
states and armies. The fact of these modifications has been used to
prove that war knows no rules. Military science rests upon principles
which can never be safely violated in the presence of an active and
skillful enemy, while the moral and political part of war presents these
variations. Plans of operations are made as circumstances may demand: to
execute these plans, the great principles of war must be observed.

For instance, the plan of a war against France, Austria, or Russia would
differ widely from one against the brave but undisciplined bands of
Turks, which cannot be kept in order, are not able to maneuver well, and
possess no steadiness under misfortunes.

ARTICLE III.

Wars of Expediency.

The invasion of Silesia by Frederick II., and the war of the Spanish
Succession, were wars of expediency.

There are two kinds of wars of expediency: first, where a powerful state
undertakes to acquire natural boundaries for commercial and political
reasons; secondly, to lessen the power of a dangerous rival or to
prevent his aggrandizement. These last are wars of intervention; for a
state will rarely singly attack a dangerous rival: it will endeavor to
form a coalition for that purpose.

These views belong rather to statesmanship or diplomacy than to war.

ARTICLE IV.

Of Wars with or without Allies.

Of course, in a war an ally is to be desired, all other things being
equal. Although a great state will more probably succeed than two weaker
states in alliance against it, still the alliance is stronger than
either separately. The ally not only furnishes a contingent of troops,
but, in addition, annoys the enemy to